Month: April 2010

If you remember the Group as Layer patch I did before it suffer from several small drawbacks, mainly in the GUI part and not in the conceptual level. Also I must confess that my previous patch was awfull to review and apply 😛
So I take some time to rewrite it from scratch and improve it a little. Now is much more functional and easy to apply/integrate than before!

This patch basically add the posibility to toggle visualization, selectability (freezing) and renderability of entire groups of objects , replicating the functionality of a layer manager because groups could be already renamed and managed in ways that a layer manager could not do, that´s why I called it Groups as Layers patch but its main intention is not that, just extend the functionality of groups in the outliner in a natural and very needed way:

If you want to be able to arrange your objects in logic ways, for example, the most basic realistic mechanic modeling could have hundreds of parts, then 20 layers is not enough, you want a layer named bolts, other named gears, and many more that soon will pass the 20 limit 😉

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WOW! I’ve almost skipped the date, but this month Tinker Code (previously True Volumetrics 😉 ) has its second birthday. I’m very happy because this blog marks the same time I started with Blender as a green dev (and I still consider myself as a newbie).

This blog has seen many of the first draft of things that later with the help of the excellent Blender devs and the community became little jewels and I’m very happy for that.

A few years ago, when I saw a CG movie with FX’s or a 3D app capable of incredible effects I thought it was plain magic, believe me, I had NEVER imagined myself entering this world, but then I learned that the only thing I needed was passion, time and the same curiosity that a child has when he breaks his loved toy car to see the engine:

You learn to swim in the water, so my best advice to the ones that want to be blender devs is permanently in the title of this blog: Tinkering blender code 😉

And what better present than a shinny new branch? Thanks to Theeth and Jahka (and the rest of the devs) I now have a Blender branch to make public my tinkerings and recent developments. YAY!!!!!!!

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A few minutes ago, Jahka committed the subframe feature patch for the particle system with a few useful changes. As explained in previous post ,subframe helps to increase the stability of particle simulations.

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Stability is one of the most desired feature of a simulation and in particle systems is a must have. The fluid particles exhibit random explosions (which I think could be reduced because in older SVN revisions that does not happen) and in general the particle systems have a leaking trough wall containers behavior when the container rotates. (think of the typical wine glass falling example 🙂 )
As a suggestion from Jahka and several members of the community I have implemented particle subframe simulations not just for particle fluids but for the whole particle system.http://www.pasteall.org/12304/diff

Subframe simulations greatly increase the stability of the simulation to any desired level, it basically perform a user defined number of pre-simulations in between frames, allowing finer grain sims, and a nice side effect of it is that now particle-surface collisions could be properly captured so there’s no leaking effect when containers rotates.

Subframe simulations do increase the calculation time proportionally to the number of sub-steps, so the user has to made a trade-off between stability and simulation time. But the good news is that there’s now a lot of methods to reach stability in the particle systems so a combination of them will help to get very low substeps (even none) to get stable simulations and very fast proper particle collision detection.

Here are some examples:

2 subframes (you don’t even want to see no subframes 😉 )

4 subframes

6 subframes

Fluid in rotating container, with no subframe

Fluid in rotating container, with 5 subframes

Newtonian particles with a rotating container and no subframe

Newtonian particles with a rotating container and 4 subframes

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First of all I’m very glad the fluid particle core is now committed thanks to Jahka and also he has fixed the moving emitter object bug, but aside of that there’s no other bug. Unstable simulations are not bugs but limitations of the current solver (and actually limitations of the SPH theory, it is not unconditionally stable)
In Realflow you could get very easy unstable sims too 😉

The videos I have recorded explicitly say that where form a previous patch version, lots of things have changed after that.. And I’m working now on a proper and official documentation and later on improving stability.

If someone have problematic setups try to send it at farsthary84@gmail.com
but an important advice is that with fluid particle colliders should have friction and damping around 0.5 or higher values!

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When someone think about volumetrics the first thought that came to his mind are clouds, smoke, fire… but actually volumetric is everything, and with care and patience many material types could be achieved. The advantage of volumetric solids are that you could have procedurally infinite detail without adding geometry at all (render time will not be free but in solid volumetrics each ray integrate only few steps so are faster that gaseous volumetrics)

For example here are some tests from an excelent door model that I have downloaded from Blendswap where I have applied a solid volumetric material, first the default solid model:

This is the volumetric rendering without composition, currently volumetrics seems to not cast shadows on other volumetrics …. something to look soon.seems that volumetric dosent cast shadows on other volumetrics ....

And here I have composited the solid rendering with correct shadows to the volumetric rendering: much better 🙂Composited image

And finally a very interesting discovery I have made: using the constant integrator parameter step a cell shade effect or cartoon shading could be achieved with volumetrics! seems that sky is the limit 🙂Constant step 0.1Constant step 0.2Constant step 0.22

For the amount of detail gained and the correct shading with every ligthing enviroment possible (except fake GI) solid volumetric perform very fast and i think should be considered as an alternative to some texture/displacement traditional methods.

Cheers Farsthary

PD: Before you ask, fluids are on the way of being committed by Jahka very soon, once integrated the engine, I will resume mi work on surfacing 🙂